Medical device leak sensing devices, methods and systems

ABSTRACT

Features for protecting against leaks in a fluid circuit are disclosed. In an embodiment, a first indicator of a leak is used to trigger confirmation by blood flow reversal and air detection in the blood circuit. A method for performing a blood treatment includes, at blood treatment machine, pumping blood to a patient through a first blood line. Further, at a controller of the blood treatment machine, a first signal is received, indicating a probability of a leak in the first blood line. Responsively to the first signal, the controller commands a leak verification operation and receives a second signal indicating whether a leak in the first blood line is verified. Further, a leak indicating signal is generated if the second signal indicates a leak is verified.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a divisional of U.S. patent application Ser.No. 14/238,434, filed Jul. 18, 2014, which is a national stage entry ofInternational Application No. PCT/US12/50965, filed Aug. 15, 2012, whichclaims the benefit of U.S. Provisional Application No. 61/523,752,entitled MEDICAL DEVICE LEAK SENSING DEVICES, METHODS, AND SYSTEMS,filed Aug. 15, 2011, the entirety of all of which is hereby incorporatedby reference herein.

FIELD

The present invention relates to the detection of leaks in fluidcircuits and to devices for supporting fluid circuit components and forconnecting the same to treatment machines.

BACKGROUND

Many medical procedures involve the extraction and replacement offlowing blood or other biological fluid such as plasma from, and backinto, a donor or patient. When the fluid is outside the patient it isconducted through machinery that processes the fluid. Examples oftreatment processes include, but are not limited to, hemodialysis,hemofiltration, hemodiafiltration, blood and blood component collection,plasmapheresis, apheresis, and blood oxygenation.

The processes listed above, and others, may involve the movement oflarge amounts of fluid at a very high rate. For example, 500 ml of bloodmay be drawn out and replaced every minute, which is about 5% of thepatient's entire supply. If a leak occurs in such a system, the patientcould be drained of enough blood in a few minutes to cause loss ofconsciousness and even death. The lost blood and other fluids may poseother risks including economic and health risks. As a result,extracorporeal fluid circuits are normally used in very safeenvironments, such as hospitals and treatment centers, and attended byhighly trained technicians and doctors nearby. Even with closesupervision, a number of deaths occur in the United States every yeardue to undue blood loss from leaks.

Leaks can occur for various reasons, among them: extraction of a needle,disconnection of a luer, poor manufacture of components, cuts in tubing,and leaks in a catheter. However, in terms of current technology, themost reliable solution to this risk, that of direct and constant trainedsupervision in a safe environment, has an enormous negative impact onthe lifestyles of patients who require frequent treatment and on laborrequirements of the institutions performing such therapies.

Approaches for detecting leaks are described, for example in U.S. Pat.No. 5,674,390, which employs fluid detectors outside the fluid circuitto detect the presence of fluid after it has leaked. Another system thatemploys leak detectors external to a blood circuit is U.S. Pat. No.7,040,142. U.S. Pat. No. 6,572,576 and U.S. Patent Publication No.2008-0214979 (which was issued as U.S. Pat. No. 8,002,727 on Aug. 23,2011) describe methods of detecting leaks in which flow is reversed todraw air into a positive pressure part of a leaking blood circuit (e.g.,venous lines returning blood to the patient) so that air can be detectedand the leak identified automatically.

Yet another method for detecting a leak in a fluid circuit, for examplea vascular access, is to monitor the pressures in the arterial andvenous lines and compare their levels and changes therein to leakprofiles, thereby permitting machine detection of a leak. An example ofsuch a system is described in U.S. Pat. No. 6,221,040. The former fourU.S. patents and one patent Publication, identified immediately aboveare hereby incorporated by reference in their entireties herein. In theprovisional phase of this application, the above four patents and patentpublication were attached as Appendices I, II, III, IV, and V.

Leak safe systems have also been proposed which rely on the detection ofleaks by detecting fluid outside an expected flow path. For example, aresistance between two spaced dry electrodes may drop precipitously whenwetted by blood or other fluid. The change in resistance may be detectedby a galvanometer and used to generate an alarm signal.

There is a continuing need in the art for ultra-safe systems that can beused in a non-clinical setting and/or without the need for highlytrained and expensive staff. Reliable mechanisms to preventing anddetecting leaks of blood and other fluids are desirable. The detectionof leaks involves a trade-off between sensitivity and the frequency offalse detection. If a system is overly sensitive, there is a high riskof many false alarms, which can lead to operator “alarm fatigue” whichcan cause operators to cancel alarms without duly investigating thecause. Such a response to alarm fatigue can subvert the function ofsensitive leak detection.

SUMMARY

The disclosed subject matter employs two mechanisms for blood leakdetection which may be combined in a single system with multiple othermechanisms. In a first mechanism, a blood circuit is enclosed in aclosely conforming enclosure that prevents fluid from escaping withoutrequiring a fluid-tight seal and conducts any leaking fluid to anexternal leak detector. The enclosure provides convenient access forloading and can accept fluid circuits encased within cartridges and barefluid circuits. In a second mechanism, a leak is preliminarily detectedusing one or more highly sensitive detection devices, such as a timerate of change of pressure in a blood line. A preliminary leak detectionsignal is used to trigger a reversal of the flow of fluid, which createsa negative pressure in the normally positive pressure line, which forcesair to be drawn into the line if a leak is actually present. If air isdrawn in, then a leak is indicated by a corresponding output.

Embodiments of the disclosed subject matter include a packaged fluidcircuit for a blood treatment system with a treatment cartridge-typesupport having a folding clamshell configuration defining internalrecesses that at least partly enclose portions of a fluid circuit, thefluid circuit having tubing portions and connector portions. The tubingportions have extending sections that extend outside the support,emerging from tubing openings in a cartridge. The cartridge defines ahorn-shaped one of the openings in the cartridge that is formed bybringing two halves of a foldable sheet together, the horn-shapedopening progressively narrowing to a cylindrical recess defined betweenconcave recesses in each half of opposing portions of the foldablesheet. The extending sections being coiled in a loop with a restraint toretain the coil and hold it on the support such that the tubes extendthrough the horn shaped ports in an arc into the coil without kinking.

In other embodiments, a packaged fluid circuit for a blood treatmentsystem includes a treatment cartridge-type support having a foldingclamshell configuration defining internal recesses that at least partlyenclose portions of a fluid circuit, the fluid circuit having tubingportions and connector portions. The folding clamshell structure has aliving hinge portion where facing panels of the support meet. The hingeportion has a leak sensor positioned at approximately a lower portion ofthe support such that leaks arising from portions of the fluid circuitlying between the panels is conveyed toward the hinge portion andtherealong to the leak sensor.

Embodiments of the disclosed subject matter include a system thatreverses the flow of blood in an extracorporeal treatment system inresponse to a pressure signal. A change in pressure of an arterial lineis detected by a pressure sensor located to detect pressure of bloodbeing conveyed in a positive pressure line. A temporal pressure profilemay be acquired which shows a time-variation in pressure in the line.This profile may be stored digitally as a time series of pressure levelsamples according to various known techniques, for example using astrain gage type pressure sensor (e.g., drip chamber, chamberlesssensors, pod-type pressure sensors using diaphragm isolators, etc.) andan analog-to-digital converter, along with appropriate processor,memory, and non-volatile or volatile data storage. The profile may becompared to a template stored in memory at regular intervals by featurematching such as correlation. In such embodiments, a drop below athreshold in the correlation coefficient of the template relative to aninstant profile segment may be used to indicate a loss of normalpressurization associated with normal operation and thereafter signal analarm. In an embodiment, the pressure change may be a result of a leak(sudden drop of pressure) or a sudden change in position of the patientor movement of the arterial line and is used to trigger a reversal ofthe blood flow in the positive pressure line to test for the inspirationof air into the line using air bubble detectors which are well known inthe art. Thus, in the event of an indication of an abnormal pressureprofile or condition, the blood flow is reversed in accord with themethod and system described in U.S. Pat. Nos. 6,572,576 and 8,002,727.If a leak is not detected, an alarm may not be generated even though thepressure detection alone indicated it. Alternatively, the alarm levelmay be lower since there was a failure of both methods to detect theleak.

A feature of the two step system is that the use of a first leveldetection, such as pressure change in the blood lines, which does notrequire reversal, is used to trigger what may be a more disruptive test,or confirmation, namely the reversal of flow of blood. In this wayreversals may occur less often than in the prior art systems. Also,false positives may occur less often than in the prior art system thatrelies on pressure measurement. Other devices for recognizing thepressure loss in blood lines may be employed in combination with theabove or alone in various types of systems.

According to embodiments of the disclosed subject matter, a fluidhandling device for a medical treatment system may have a first fluidcircuit configured to process and convey fluid including at least oneactuator portion and at least one sensor portion. A second fluid circuitencases the first fluid circuit and is arranged to convey fluid leakingfrom the first fluid circuit to a leak detection portion thereof. Theleak detection portion contains a leak sensor or is configured to engagewith a leak sensor. The first and second fluid circuits may be parts ofa disposable component configured for use with a predefined medicaltreatment device. The first fluid circuit may have tube portions and thesecond fluid circuit may have tube-shaped channels that surround theportions first fluid circuit tube portions. The second fluid circuit mayhave windows that expose respective ones of the at least one actuatorportion and the at least sensor portion. Each of the windows may have anextension at a lower end thereof configured to capture leaking fluiddripping from a respective one of the at least one actuator portion andat least one sensor portion. The second fluid circuit may have a curvedtubing management recess configured to receive and support tubularextensions from the first fluid circuit. The first fluid circuit mayinclude a medical treatment component. The second fluid circuit leakdetection portion may be transparent. The first fluid circuit mayinclude a dialyzer filter and a blood circuit. The medical treatmentdevice may be configured to perform an extracorporeal blood treatment.The first fluid circuit may include a dialyzer filter and a bloodcircuit. The first and second fluid circuits may form a generally planararrangement and the first fluid circuit may include connectors exposedby respective windows. The first and second fluid circuits may form agenerally planar arrangement and the first fluid circuit may includeconnectors exposed by respective windows and configured to connect to adialysate fluid circuit of a dialysis machine. The first fluid circuitmay include a blood treatment filter having a longitudinal axis; thesecond fluid circuit is configured to support the blood treatment filterat a predefined angle with respect thereto; and the predefined bloodtreatment device is configured to hold the second fluid circuit in apredefined orientation such that the blood treatment filter longitudinalaxis is held diagonally with one end above the other. The predefinedblood treatment device may be configured such that the predefinedorientation places the second fluid circuit leak detection portion at abottom of the second fluid circuit. The second fluid circuit may beconfigured to open as a clamshell to receive the first fluid circuit.The second fluid circuit may be closed around the first fluid circuitsuch that a first portion thereof fits within a recess of the other. Thesecond fluid circuit may have interior-facing surfaces, wherein all ofthe interior facing surfaces are sloped such that fluid leaking from thefirst fluid circuit are conveyed to the leak detection portion.

According to embodiments of the disclosed subject matter, a fluidhandling system for a medical treatment system has a treatment devicehaving at least one actuator and at least one sensor. A first fluidcircuit is configured to process and convey fluid including at least oneactuator portion and at least one sensor portion configured to engagethe at least one actuator and the at least one sensor. The treatmentdevice has a leak detector and further configured to enclose the firstfluid circuit and to convey any leaks from the first fluid circuit tothe leak detector. A second fluid circuit is configured to process andconvey fluid including at least one actuator portion and at least onesensor portion. A third fluid circuit encases the fluid circuit and isarranged to convey fluid leaking from the first fluid circuit to a leakdetection portion thereof. The leak detection portion is configured toengage the leak detector. The third fluid includes at least one actuatorportion and at least one sensor portion configured to engage the atleast one actuator and the at least one sensor. The second and thirdfluid circuits form a unitary fluid circuit device. As a result of thisconfiguration, the treatment device is configured to detect leaks usingeither the unitary fluid circuit device or the first fluid circuit. Theunitary fluid circuit device may be a disposable. The treatment devicemay include a blood treatment device.

According to embodiments of the disclosed subject matter, a method forperforming a blood treatment in which a blood treatment machine pumpsblood to a patient through a first blood line. A controller of the bloodtreatment machine receives a first signal indicating a probability of aleak in the first blood line. The controller, responsively to the firstsignal, commands a leak verification operation and receiving a secondsignal indicating whether a leak in the first blood line is verified.The controller generates a leak indicating signal if the second signalindicates a leak is verified. The controller may be configured tocontrol a rate and direction of the pumping and the leak verificationoperation may include reversing a flow of blood in the first blood lineand detecting air in the first blood line. The method may includegenerating the first signal, wherein the generating the first signal mayinclude detecting a change of pressure in the first blood line. Themethod may include generating the first signal, wherein the generatingthe first signal may include detecting a rate of change of pressure inthe first blood line. The method may also include generating the firstsignal, wherein the generating the first signal may include detecting acharacteristic of a pressure versus time signal characterizing a flow inthe first blood line.

According to embodiments of the disclosed subject matter, a system forperforming a blood treatment can include a blood treatment componentwith a controller configured to pump blood to a patient through a firstblood line. The controller is configured to receive a first signalindicating a probability of a leak in the first blood line. Thecontroller is configured to, responsively to the first signal, command aleak verification operation and receiving a second signal indicatingwhether a leak in the first blood line is verified. The controller isconfigured to generate a leak-indicating signal responsively the secondsignal. The controller may be configured to control a rate and directionof the pumping and the leak verification operation may include reversinga flow of blood in the first blood line and detecting air in the firstblood line. The controller may be configured to generate the firstsignal responsively to a detection of a change of pressure in the firstblood line. The controller may be configured to generate the firstsignal responsively to a detection of a rate of change of pressure inthe first blood line. The controller may be configured to generate thefirst signal responsively to a detection of a characteristic of apressure versus time signal characterizing a flow in the first bloodline.

According to embodiments of the disclosed subject matter, a bloodtreatment apparatus includes a blood treatment component configured topump blood from an arterial blood line to a venous blood line. A leaksensor is configured to detect a leak with a probability of less thanunity in the venous blood line. An air detector is configured to detectinfiltration of air into the venous blood line. A blood flow reversingdevice is controlled by a controller. The controller receives a signalfrom the sensor and configured to reverse flow responsively to a signalfrom the leak sensor such that air infiltrating the venous blood line isdetected by the air detector. The leak sensor may include a pressuresensor configured to detect pressure changes in the venous blood line.The leak sensor may include a data store configured to record a timeseries of pressure samples representing pressure in the venous bloodline and a processor configured to determine a magnitude of a change inpressure within a predefined time interval. The leak sensor may includea data store configured to record a time series of pressure samplesrepresenting pressure in the venous blood line and a processorconfigured to determine a magnitude of a change in pressure within apredefined time interval and to indicate a leak when a rate of change inpressure exceeds a predefined range.

According to embodiments of the disclosed subject matter, a fluidcircuit device can include a support and at least one tubular element.The support can have an interior space and can be generally planar inconfiguration with a perimeter. The at least one tubular element canhave a first portion encased within the interior space and a secondportion extending through an opening of the support to an outside ofsaid interior space. The opening can have a curved guide shaped toprevent the second portion from kinking when the second portion is drawntightly to at least one side of an axis of the opening. More than one ofthe openings can be provided. The second portion can be coiled in a flatloop adjacent the support and within the perimeter. The opening can faceat least partly in a direction perpendicular to a major planar surfaceof the support. The curved guide can curve so that one end of thesupport is more parallel to a major planar surface of the support thananother end of the curved guide such that the second portion is liftedaway from the interior space. The curved guide can curve in a plane thatis parallel to a major planar surface of the support. The second portioncan extends toward the perimeter and can curve along and then inwardlyfrom the perimeter back into a portion of the interior space that has ahold down member which confines the second portion within the interiorspace and defines a gap through which the second portion can be pulledout of confinement in the interior space in a direction perpendicular tothe major planar surface so as to permit the second portion to extenddirectly away from the opening along the axis thereof. Alternatively,the second portion can extend toward the perimeter and can curve alongand then inwardly from the perimeter back into a portion of the interiorspace that has a hold down member which confines the second portionwithin the interior space and defines a gap through which the secondportion can be pulled out of confinement in the interior space in adirection parallel to the major planar surface so as to permit thesecond portion to extend directly away from the opening along the axisthereof. The support can be of two panels whose surfaces each define asingle valued function such that it can molded and released from avacuum mold.

In embodiments of the disclosed subject matter, a fluid circuit devicecan include a support and at least one tubular element. The support canhave an interior space and can be generally planar in configuration witha perimeter. The at least one tubular element can have a first portionencased within the interior space and a second portion extendablethrough an opening of the support to an outside of said interior space.The support can have guides that releasably hold the second portionwithin the perimeter and at least one curved guide shaped to preventkinking of or damage to the second portion when so held within theperimeter. The guides can be arranged and positioned to permit thesecond portion to be coiled in a flat loop within the perimeter. Thesupport can be of two panels whose surfaces each define a single valuedfunction such that it can molded and released from a vacuum mold. Thesupport can have a partially sealed volume and can be sealed around theperimeter with openings for the second portion and to provide access tosensor and actuator portions of the circuit. The support can have acontinuous fluid-tight seal along the perimeter can be configured formounting to a predefined device in a particular orientation such thatthe opening is located in an upper half of said support. The support canbe configured for mounting to the predefined device in a particularorientation such that the opening is located adjacent a top of saidsupport.

In embodiments of the disclosed subject matter, a method for performinga blood treatment can include, at a blood treatment machine, pumpingblood to a patient through a first blood line, and, at a controller ofsaid blood treatment machine, receiving a pressure signal indicating aloss of pressure in said first blood line. The method can furtherinclude, at the controller, responsively to the first signal, commandinga leak verification operation, receiving a second signal indicatingwhether a leak in the first blood line is verified responsively to theleak verification operation, and generating a leak indicating signal ifthe second signal indicates a leak is verified. The controller can beconfigured to control a rate and direction of the pumping and the leakverification operation can include reversing a flow of blood in thefirst blood line and detecting air in the first blood line. The methodcan further include generating the first signal. The generating thefirst signal can include detecting a change of pressure in the firstblood line.

In embodiments of the disclosed subject matter, a method for performinga blood treatment can include, at blood treatment machine, pumping bloodto a patient through a first blood line, and, at a controller of theblood treatment machine, receiving a first signal of a first classifierof a leak. The method can further include, at the controller,responsively to the first signal, commanding a leak verificationoperation, receiving a second signal of a second classifier indicatingthe presence of a leak, which second signal is responsive to the leakverification operation, and generating a leak indicating signalresponsively to the second signal. The leak verification operation caninclude halting a flow of fluid and/or reversing a flow of fluid.Alternatively or additionally, the leak verification operation caninclude applying a voltage or acoustic signal to a fluid and detectingthe transmission or reflection responsively thereto. The secondclassifier can detect pressure signals indicative of patient vital signsand/or air in a fluid line and/or a current or pressure signal.

In embodiments of the disclosed subject matter, a method for performinga blood treatment can include, at blood treatment machine, pumping bloodto a patient through a first blood line, and, at a controller of theblood treatment machine, receiving a first signal indicating aprobability of a leak in said first blood line. The first signal can begenerated responsively to a predefined change in the pressure in thefirst blood line and/or responsively to a calculation that is responsiveto a constant pressure occurring before and after the predefined changein the pressure in the first blood line. Alternatively or additionally,the first signal can be responsive to pressure data stored in a buffer.Alternatively or additionally, the first signal can be responsive tofiltered pressure data stored in a buffer, which data is filtered toremove at least one of pump noise and high pass frequency components.Alternatively or additionally, the first signal can be generatedresponsively to a change of 17% in the pressure in the first blood lineoccurring between two intervals during which the pressure remainedwithin a predefined range for a predefined time. Alternatively oradditionally, the first signal can be generated responsively to a changeof a predefined magnitude in the pressure in the first blood lineoccurring between two intervals during which the pressure remainedwithin a predefined range for a predefined time. Alternatively oradditionally, the first signal can be generated responsively to a changeof a predefined percentage of magnitude in the pressure in the firstblood line occurring between two intervals during which the pressureremained within a predefined range for a predefined time. The method canfurther include, at the controller, responsively to the first signal,commanding a leak verification operation and receiving a second signalindicating whether a leak in the first blood line is verified. Thecontroller can be configured to control a rate and direction of saidpumping and said leak verification operation includes reversing a flowof blood in said first blood line and detecting air in said first bloodline. The method can further include, at the controller, generating aleak indicating signal if the second signal indicates a leak isverified.

In embodiments of the disclosed subject matter, a method for detecting aleak in a blood flow line can include storing a time series of pressuredata representing pressure in the blood flow line over time in a bufferof a controller of a blood processing device, detecting a signature in adata stored in the buffer. The signature can be adjacent intervalsduring which the pressure remained within a first predefined range ofvariation (peak to peak or variance) for a predefined time (plateauintervals), combined with a difference between a pressure representativeof the two pressures during the plateau intervals exceeding a secondpredefined range. The second predefined range can be defined in terms ofpercentage magnitude change. The second predefined range can be definedin terms of absolute magnitude change.

In embodiments of the disclosed subject matter, an apparatus forperforming a blood treatment can include a blood pump, sensors,actuators, a controller, and a memory. The sensors and actuators can beconfigured to engage with predefined blood lines including a venous lineand an arterial line connectable to an access for returning blood to,and drawing blood from, a patient. The sensors can include a venouspressure sensor and an arterial pressure sensor configured to measurepressure in the venous and arterial lines, respectively. The controllercan be connected to the blood pump. The memory can be in the controllerand can store a procedure for storing time sequences of pressuresindicated by the arterial and venous pressure sensors. The controllercan be programmed to halt the blood pump responsively to a combinationof both of the time sequences. The combination can include detection ofa fall in pressure in the venous line that coincides with a stablepressure in the arterial line. The controller can be further configuredto reverse a flow of blood responsively to the combination andthereafter, to halt the blood pump responsively to a detection of air inone of the blood lines.

In embodiments of the disclosed subject matter, an apparatus forperforming a blood treatment can include a blood pump, a pressuresensor, and a control module. The blood pump can be constructed to pumpblood to a patient through a first blood line. The pressure sensor canbe coupled to the first blood line for measuring a pressure therein. Thecontrol module can be configured to generate a first signal indicating aprobability of a leak in the first blood line responsively to apredefined change in the pressure in the first blood line as measured bythe pressure sensor. The control module can be configured to generatethe first signal responsively to a predefined change in the pressure inthe first blood line and responsively to a calculation that isresponsive to a constant pressure occurring before and after thepredefined change in the pressure in the first blood line. The apparatuscan also include a buffer for storing pressure data therein. The firstsignal can be responsive to the pressure data stored in the buffer. Thecontrol module can be configured to subject the pressure data stored inthe buffer to filtering so as to remove at least one of noise from saidblood pump and high-pass frequency components. Alternatively oradditionally, the control module can be configured to generate the firstsignal responsively to a change of a predefined magnitude or percentagein the pressure in the first blood line occurring between two intervalsduring which the pressure remained within a predefined range for apredefined time. The apparatus can also include a second control modulefor controlling the blood pump. The second control module can beconfigured to command a leak verification operation in response to thefirst signal. The apparatus can further include a detector configured todetect air in the first blood line. The second control module can beconfigured to control a rate and direction of the blood pump. The leakverification operation can include reversing a flow of blood the in afirst blood line and using the detector to detect air in the first bloodline. The second control module can be configured to generate a leakindicating signal when the detector detects air in the first blood line.

In embodiments of the disclosed subject matter, a controller for a bloodtreatment machine can be configured to generate a first signalindicating a probability of a leak in the first blood line responsivelyto a predefined change in pressure in the first blood line. The bloodtreatment machine can have a blood pump that pumps blood to a patientthrough the first blood line. The controller can be configured togenerate the first signal responsively to a predefined change in thepressure in the first blood line and responsively to a calculation thatis responsive to a constant pressure occurring before and after thepredefined change in the pressure in the first blood line. A buffer canbe provided for storing pressure data therein. The first signal can beresponsive to the pressure data stored in the buffer. The controller canbe configured to subject the pressure data stored in the buffer tofiltering so as to remove at least one of noise from said blood pump andhigh-pass frequency components. Alternatively or additionally, thecontroller can be configured to generate the first signal responsivelyto a change of a predefined magnitude or predefined percentage in thepressure in the first blood line occurring between two intervals duringwhich the pressure remained within a predefined range for a predefinedtime. The controller can be configured to command a leak verificationoperation in response to said first signal. The controller can beconfigured to control a rate and direction of the blood pump. The leakverification operation can include reversing a flow of blood the in thefirst blood line and detecting air in the first blood line. Thecontroller can be configured to generate a leak indicating signal whenair is detected in the first blood line.

In embodiments of the disclosed subject matter, an apparatus can beprovided for performing any of the methods disclosed herein. Inembodiments of the disclosed subject matter, a controller can beprogrammed to implement any of the methods disclosed herein. Inembodiments of the disclosed subject matter, a computer readable mediumcan have recorded instructions for implementing any of the methodsdisclosed herein.

Objects and advantages of embodiments of the disclosed subject matterwill become apparent from the following description when considered inconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments will hereinafter be described in detail below with referenceto the accompanying drawings, wherein like reference numerals representlike elements. The accompanying drawings have not necessarily been drawnto scale. Where applicable, some features may not be illustrated toassist in the description of underlying features.

FIGS. 1A and 1B show a support structure that encases a fluid circuitand guides any leaks to a leak detector, according to embodiments of thedisclosed subject matter.

FIG. 1C shows a fluid handling device with features for supporting andengaging an encased fluid circuit according to the embodiment of FIGS.1A and 1B.

FIG. 2 shows a show a support structure that encases a fluid circuit andguides any leaks to a leak detector according to another embodiment ofthe disclosed subject matter.

FIG. 3A shows the embodiment of FIG. 2 in a configuration for packagingwhere tubing lengths that form part of a fluid circuit are coiled toform a compact bundle wherein features of the supporting structure helpto prevent tubing kinks in packaged fluid circuits.

FIG. 3B shows an encasing portion of the support structure of FIG. 3A inan unfolded configuration as may be formed by vacuum molding ofthermoplastic.

FIGS. 4A through 4C show features of encasing structures which permitaccess to a fluid circuit portion while providing for guiding leaks to aleak sensor according to further embodiments.

FIGS. 5A through 5D show features of encasing structures which permitaccess to a fluid circuit portion while providing for guiding leaks to aleak sensor, according to embodiments of the disclosed subject matter.

FIGS. 6A and 6B show a permanent housing that contains links and detectsthe leaks for a fluid circuit according to an embodiment of thedisclosed subject matter.

FIGS. 6C and 6D show a permanent housing that contains links and detectsthe leaks for a fluid circuit according to another embodiment of thedisclosed subject matter.

FIGS. 7A and 7B show an embodiment of a housing that contains links anddetects the leaks for a fluid circuit which is configured to support asupport structure that encases the fluid circuit and guides any leaks toa leak detector and a fluid circuit without an encasing support,respectively.

FIG. 8 shows a further embodiment of a permanent housing that containslinks and detects the leaks for a fluid circuit, including fluidhandling component such as sensors and actuators.

FIG. 9 is a schematic of a fluid handling system with featuresconfigured for leak detection, according to embodiments of the disclosedsubject matter.

FIG. 10 illustrates a leak detection algorithm that forms part of a leakdetection method and system.

FIG. 11 illustrates features of a blood treatment device which may beused to implement features of the embodiments of FIGS. 9 and 10.

FIG. 12 is a flow chart showing a procedure for a two-stage leakdetection system and method according to embodiments of the disclosedsubject matter.

FIGS. 13 through 18 show fluid circuit support embodiments and featuresthereof to illustrate subject matter that, among other things, protectstubing against kinking and injury to the tubing and facilitatespackaging.

FIG. 19 shows detection and control system features for implementingembodiments of the system and method of FIG. 20.

FIG. 20 describes a leak detection method and system and specificalternative embodiments.

FIG. 21 is a flow chart showing a procedure that may be used for a firstof the two-stage leak detection system and method described with regardto other embodiments, for example, in place of S14 in FIG. 12.

FIG. 22 is a graph illustrating pressure fall detection based on plateaudetection and a fall in a filtered venous pressure signal, according toone or more embodiments of the disclosed subject matter.

DETAILED DESCRIPTION

Referring to FIGS. 1A and 1B, a support structure 102 is a foldingarticle of manufacture that is configured to enclose at least portionsof one or more fluid circuits 101 so as to contain leaks and guide fluidfrom a leak at any point in the fluid circuit 101 to one or morelocations where a sensor can detect the leak. Tube segments of thecircuit may be enclosed by trough channels 128 and recesses of othershapes configured correspondingly to enclose other features of thefluid. In the illustrated embodiment, the support structure 102 has aliving hinge portion 136 and various recesses such as recess 114 andcutouts such as 110, 116. The fluid circuit 101 has tubing sections 122and 124 and other components, such as a treatment component 120, whichare supported in respective parts of the support 102 by molded troughs112 which surround the tubing sections 122 thereby containing leaks andhelping to convey them. When the support 102 (originally in aconfiguration such as discussed with reference to FIG. 3B) is closed inthe fashion of a book about the hinge portion 136, it forms a sealedcontainer except for access windows discussed below.

Recesses 114 enclose opposite sides of a treatment component 120, whichmay be, for example, a filter, a dialyzer, hemofilter, absorbent,oxygenator or other device. Cutouts 110, 116 expose portions of thefluid circuit 101 such as a tubing section 124 for pumping, allowing itto be engaged by actuators or sensors of a machine 150 with which thesupport structure engages (see FIG. 1C and attending discussion). Flowguides 128 may also be molded into support structure 102 to guideleaking fluid toward the hinge portion 136 which may further guide leakstoward a leakage sensor 106 or a portion 132 of the support structure102 where a leak sensor may be disposed to detect leaks. These flowguides may be in addition, or alternatively, to the troughs that enclosetubes and other recess features that contain fluid circuit elements. Inaddition, or alternatively, leaking fluid may be guided by a spacebetween the flat portions 123 of the support structure 102 such thatthere are seams inter-attaching the facing flat portions (as indicatedat 123, for example) of support structure 102.

The support structure 102 may be configured with a leak sensor 106forming part of the support structure or it may convey fluid to aportion 132 of the support structure 102 where an external leak sensorcan be disposed (not shown in the present figure but see discussion ofFIG. 7B, for example). As shown in FIG. 1B, the support structure 102may be installed on a treatment machine (not shown) having sensors andactuators as well as connectors to other fluid sources and sinks. Thesupport structure and treatment machine may be configured to hold thesupport structure at an angle with respect to the direction of gravitysuch that leaking fluid falls toward the sensor 106.

As shown in FIG. 1C, a fluid handling machine 150, for example, a bloodtreatment device, may have a fixture 152 configured to receive thesupport structure 102. The arrangement of the fixture 152 may be suchthat the component parts of the support structure are oriented andaligned with sensors 158, 154, and actuators 156 and 160 of the machine150. In an example embodiment, the blood treatment machine may have pumpand valve actuators and pressure, temperature, and leak detectionsensors. The fixture 152 may be a recess in a face of the machine, forexample, that receives the frame of the support structure 102 to hold itin a specific position and orientation. Actuators and sensors may movewith respect to the machine 150 to engage the elements of the fluidcircuit 101 held by the support structure 102. In the illustratedembodiment, a leak sensor 154 is positioned at a lowest position inorder that gravity may drive all leaking fluids toward it. Inembodiments, the fixture 152 may include a recess that captures andguides fluids to the leak sensor 154 in case some breach the enclosingstructure.

The machine 150 may be configured with a controller 109 and measurementindicators such as a display output for a computer display thatindicates leaks when detected. Alternatively the machine 150 can beconfigured with one or more annunciators 108 that may be used togenerate an alarm output upon detection of a leak. Alternative outputsinclude data signal such as a digital signal containing a message. Otheralternative outputs may be employed including automated phone (e.g. cellphone) messages to a call center, data log outputs and other outputsignals. For a leak detector that forms part of the support structure102, the location indicated at 154 may represent electrical contacts ora magnetic pickup configured to receive an indication from the sensor(e.g., as indicated at 106 in FIGS. 1A and 1B) and convey a leakindication signal to the 109 controller of the machine 150. Thecontroller 109 manages these functions and which may be integrated inthe machine 150, and may include a digital controller employing avariety of known devices and methods. Systems and types of outputs andalarms as well as devices and systems for generating them are describedin the incorporated references identified above.

Many other kinds of elements may be included in the fluid circuit 101and the illustration is merely figurative to highlight certain featuresof the device. FIG. 2 shows a configuration of a support device 200(essentially an embodiment more generally represented by the embodimentof FIG. 1A) made from a panel 204 that may be folded or cut into twohalves and welded together (the precise manner of assembly is merely aperipheral incident of the embodiment and not essential to the claimedsubject matter except as recited by the claims) to enclose a fluidcircuit (portions of which are visible at 210, 214, 216, 252, and 251,according to an embodiment of the disclosed subject matter (See alsoFIG. 3B). The present example of a support device 200 encloses a portionof a blood handling circuit for a dialysis system. The support device200 foldable panel 204 structure as shown in an unfolded configurationat 271 in FIG. 3B and shown in a folded configuration in FIGS. 2 and 3A.The general features of the present embodiment may be as described withreference to the embodiments described with reference to FIGS. 1A and1B. More detailed features are shown in FIGS. 4A-4D, 5A-5C, which arediscussed below. The treatment unit 216 may be, as in the presentembodiment, a dialyzer filter 216 (but could also be a hemofilter, bloodoxygenator or the like).

A venous blood line 210 is exposed as shown by the support device 200.An arterial line as indicated at 212 is also exposed by the supportdevice 200. The blood lines 210 and 212, exposed by openings 211 and213, respectively, are thereby enabled to engage sensors such as apressure sensor and/or temperature sensor, or a bubble sensor on a fluidhandling machine (e.g., 150). Another portion 216 of the fluid circuitis exposed for engagement with a blood component sensor, for example,one that detects leakage of blood into the dialysis fluid which isconveyed by the portion 216. A pumping portion of the arterial line 214is exposed by a window 295 of the support structure 200 to permit itsengagement with a peristaltic pump actuator of the fluid handlingmachine 150. The exposed portions may engage sensors or actuators suchas blood leak detectors (optical type) or pressure sensors, or airdetectors or pumps. Interfaces to pressure sensors may be providedinline to respective tubing segments for measurement of venous linepressure, and upstream and downstream of the pump tube segment 214 asindicated at 241.

In the embodiment shown, the dialyzer filter 216 has an air vent 206stemming from a tube 202 exposed by a cutout 203 in the support 200. Theexposed tube 202 may be clamped by an integrated automatic clampingdevice controlled by a controller of a compatible treatment machine withfeatures as discussed with reference to FIG. 1C. The exposed segment oftubing 202 may be used by the treatment machine to detect fluid as wellas to permit an automatic clamp to stop the flow of fluid. Air vent 206may be used to release air during priming of the blood circuit. Aircollects in the header of the filter as described in U.S. Pat. No.7,544,300, which is also hereby incorporated by reference as is fullyset forth herein. As priming fluid is flowed through the blood circuitduring priming, air emerges from the vent 206 (a hydrophobicmembrane-sealed port) displaced by fluid until the fluid enters the tubesegment 202 and is detected. Then the tube segment 202 is clamped. Ifthe retreat of the fluid column occurs due to the accumulation of air inthe tube segment 202, and the air retreat of the fluid detected by afluid detector, then the clamp may be released to vent the air.

Right-angle connectors 220 and 222 interface with a dialysis circuit inan embodiment of the machine 150. When the support 200 is inserted on atreatment device (embodiment of machine 150), the right-angle connectors220 and 222 automatically connect to source and drain connectors on themachine. These types of connectors may be used to interconnect anon-disposable portion of a fluid circuit, such as the non-blood circuitof a dialysis system, with the disposable portion. In embodiments, thenon-disposable portion handles fresh and spent dialysate. The connectorsmay be needle-less ports (blunt stubs that insert into self-healingsepta in the right-angle connectors 220 and 222).

Referring now also to FIGS. 3A and 4C, a curved slot 208 allows longstretches of blood tubing 251 and 252 to be inserted therethrough sothat tubes 251 and 252 do not kink. The curved slot 208 has a pair oftroughs 265 that face toward the slot 208 and curves up toward theviewer to allow the distal extent of the blood tubing 251 and 252 toextend toward a patient access end as shown in FIG. 3A. The distalextents of the tubing 251 and 252 can then be looped and then coiledinto an oval and laid over the support 200 as shown in FIG. 3A. It canbe seen in FIG. 3A that tubing 252 and 253 are also supported by a hornshaped opening 262 with a curved supporting surface that also helps toprevent kinks. In embodiments, the supporting curved surface 262 and thesupporting troughs 265 form a single continuous surface that preventskinks. The curved slot 208 is defined by overhanging portions 209 thatretain the tubes 251 and 252. The size of the curved slot 208 and thechoice of materials for the overhanging portions 209 are such that tubescan be snapped into the troughs 265 one at a time and then retained bythe overhanging portions 209.

In an alternative embodiment, the curved support 262 lie adjacent aretention mechanism that allows the distal part of the tube to bereleased by pulling in a direction parallel to the general plane of thesupport device 200. For example, the configuration of FIG. 15, discussedbelow, has a gap 645 or 646 into which the distal part of the tube canbe retained within the perimeter of the support device as discussed withreference to FIG. 15, below.

The openings through which tubes 251 and 252 extend have axes that aregenerally in a plane of the support, which is generally planar in shape.The support 200 defines a trough 258 which protects the tubing 251 and252 when resting therein as shown in FIG. 3A. The tubing may beprotected by being at least partly within the perimeter when routed asshown in FIG. 3A but even if the tubing extends slightly beyond theperimeter, if an object forces the tubing, such as when the support andcircuit are pushed into a tight box, the tubing will be pushed into thetrough 258 until the object encounters the perimeter and no further sothat the tubing will still be protected. Thus, the tubing may at allpoints reside substantially within the perimeter, though not literally,and still be protected by the support device 200.

The two panels making up the support device embodiment illustrated maybe of sheet material that defines a single valued surface function suchthat it can be formed on, and released from, a vacuum mold or othertwo-part mold. Features of the support 200 may be applied to other typesof fluid circuit support structures that do not enclose the circuit tocapture leaks. For example, an open panel or simple frame may providethe tubing guides and protection features described above. Thesefeatures may allow compact packaging without the risk of tubes beinginjured or kinked as a result of being tightly fitted in packaging,containers, or confined or forced against other objects.

By packaging the support 200 with the blood tubing with the disclosedconfiguration, kinked tubing can be avoided in packaged fluid circuitswhich can avoid the flow restrictions created by kinks. Also, kinks canincrease the risk of thrombogenesis due to turbulence induced in thewake of the flow restriction caused by them. The openings through whichthe blood tubes 252 and 251 emerge may be shaped as the horn-shapedopening 265 with the supporting curved surface 262 providing a smoothlycurved support on both sides for the blood tubing thereby furtherpreventing kinks. The looping is illustrated at 270 in FIG. 3A. The coilof tubing may be restrained with a band 272 such as a rubber band ortape. The coil may be taped or banded to the support 200 by the same oranother such band 273. Other restraints may be used to position the coilas shown. For example, see discussion below of FIGS. 13 to 17. Anotherfeature of the present and further embodiments is the distal part of thetubing may be confined within the perimeter of the support device 200such that no part of it can get trapped between the support and anexternal object. This helps safeguard against injury to, or kinking of,the tubing during shipping, storage, or other handling.

Referring also to FIGS. 3B and 4A, the panel shaped structure 271 hasrecesses 283 (one on either side with one indicated at 283) that enclosethe fluid circuit as shown in FIG. 2 when folded. The structure 271 hascorresponding trough-shaped recesses 281 for tubes, recesses 284 forconnectors, and recesses for 285 for sensor elements. FIG. 4A shows apressure pod 291 visible through an opening 276 and a connector 287visible through an opening 277. Also shown is an opening 289 for atubing segment 294. These fluid circuits are representative of elementsthat may interface with external devices. Corresponding elements may beprovided to enclose (fully or partially) and any other elements of afluid circuit to form the enclosed structure 200. The panel shapedstructure 271 may be formed from thermoplastic in a vacuum moldingprocess followed by die-cutting or any suitable process. After foldingseams (or other interconnections) may be welded or attached by solventbonding or adhesive or other suitable process. Instead of folding, thestructure 200 may be formed using separate panels or other supportelements. Referring to FIG. 4B, a slot shaped opening 275 may expose atube segment 274 for engagement with an actuator or sensor parts ofwhich lie outside the frame of the support structure.

The support device 200 may be configured to enclose enough of thecircuit element to minimize the risk of leaks escaping while permittingcircuit elements to interface with the fluid handling machine (e.g.,150) and to guide any leaking fluid to a fluid leak sensor (for example,the integrated one indicated at 106 in FIG. 1A). FIG. 5A shows aperspective view of a window of the support device 200, for example, awindow 213 as shown in FIG. 2. FIG. 5B shows section and side views ofthe configuration of FIG. 5A. FIG. 5C shows a window such as 213 insection with both the top and bottom of the frame in section view. FIG.5D shows a window structure in which a rectangular frame is angled whichmay assist in the flow of leaking fluids through a support device suchas 200. The support device 200 panels 432 may be configured to providechanneling for leaking fluid. In one embodiment, the panels 432 arewelded together at dimpled points 433 which ensure a gap 434 betweenthem is provided for leaking fluid to be conveyed between the panels 432to a leak sensor. The perimeter edges (indicated at 430 in FIG. 2) maybe welded or adhesively bonded to ensure fluid cannot leak from thesupport structure 200. Extension features 440 span a fluid circuitfeature, such as a tube 442, that is open for access (access directionindicated by arrow 402) by actuators or sensors of the machine 150 toensure that fluid leaking from the feature is captured. In additionalembodiments, channel structures may be formed into the support structure200 such as channel 413 indicated in FIG. 5A. A rectangular window 440that is angled with respect to gravity may provide advantages in termsof ensuring against the escape of fluid flowing around the window 440.For example, rather than dripping from an upper edge 441 to a lower edge443, if the window 440 were straight, fluid may flow along the upperedge 441 and down around the window 440.

Referring now to FIGS. 6A and 6B, an enclosure 300 is configured as partof a fluid handling machine with actuators and sensors generally asdiscussed with regard to the foregoing embodiments. In the presentembodiment, a fluid circuit 301 is encased in the enclosure 300. Forexample the fluid circuit 301 may have tubing portions 314 and otherelements, such as a cylindrical structure 310, which may be a dialyzeror any of the other components described in the foregoing embodiments.The enclosure includes an access hatch 302 to provide access to aninterior of the enclosure. The access hatch may pivot on a hinge 312 bywhich it is attached to a back panel 320. The configuration is shown ina closed position for operation in FIG. 6A and a partly open position inFIG. 6B. The back panel 320 and/or the hatch may carry sensors,actuators, and/or other devices that interconnect with the elements ofthe fluid circuit 301. The internal surface of the enclosure hassurfaces 321 and 304 that are configured to capture and convey any leaksto a leak sensor 322. The surfaces 304 and 321 may be sloped so as tocause any drips of fluid (as indicated for example at 316 and 317) toflow toward the leak detector 322 and accumulate there as indicated at318. In the embodiment 300, the surfaces 321 and 304 are shaped suchthat any fluid accumulating on the hatch 302 drips so as to flow to thefluid sensor 322. This can be accomplished without forming a sealbetween the panel 320 and the hatch 302, for example, if the hatch 302fits partly inside a recess 307 of the enclosure 300. A sloping portion305 may further ensure that fluid moves toward the fluid sensor 322. Ina similar arrangement, shown in FIG. 6C, a back panel recess 340receives a hatch 342 with an internal surface configured similarly tothat of the FIG. 6A, 6B embodiment. In the present embodiment, however,the hinge 344 is remote from the edge of the hatch 342. As in theprevious embodiment of FIGS. 6A and 6B, containment of leaks and theirconveyance to a detector is provided without a seal between the recess340 and hatch 342.

FIG. 7A shows the embodiment of FIG. 6A with a fluid circuit 301 that isnot enclosed in a support structure such as support structure 200 shownin FIG. 2. In the embodiment of FIG. 7A, a leak sensor 323 employs anon-wetted type of detection sensor, such as one that employs anoptical, capacitive, induction or some other non-contact mechanism fordetecting fluid. In an example embodiment, the sensor 323 is an opticalsensor that detects blood, such as the type used in blood treatmentsystem to detect the presence of small amounts of blood in a clearfluid. FIG. 7B shows the configuration of FIG. 7A with an enclosed fluidcircuit having a support structure essentially as described above, forexample with reference to FIGS. 1A and 2. A support enclosure 328supports and encases a fluid circuit 331. At 360 a sensor or actuator isshown with engagement portions 362 that engage a fluid circuit portion332, for example a tube portion. The support enclosure has a lowerportion 325 where leaking fluid may collect which is immediatelyadjacent the fluid sensor 323. Thus, as illustrated in FIG. 7B, the sameconfiguration can accept both enclosed an unenclosed fluid circuits anddetect leaks both.

Referring now to FIG. 8, an embodiment of an enclosure 450 for a fluidcircuit 453 which is generally similar to the foregoing embodiment 300in that it contains leaks from fluid circuit 453 elements and conveysany leaking fluid to a fluid sensor 468. An actuator/sensor assembly 455has various components to engage with components of the fluid circuit453. Specific features of the present embodiment permit ease ofinstallation of the fluid circuit 453 to the components of the fluidcircuit 453. A pair of right angle connectors are formed as a singleconnector component 452 to facilitate connection to a dialysis circuitbehind it (not shown in the figure). Elbows 454 help to auto-align thetubing 459 and the intermediate connector component 452. Pressure pod456 inserts directly into transducer components in a backplane 471.Pressure pods 458 and 460 insert directly in respective transducers inthe backplane and in doing so, align pump tube segment 463 with aperistaltic pump rotor 465. When a door 453 is closed, a constant forceretaining member 482 holds the connector component 452 against thehidden mating connectors in the backplane 471. The door 453 has aspring-biased pump race 462 that engages the pump tube segment 463between itself and the peristaltic pump rotor 465. A filter 451 isreceived in a trough 493 and enclosed by a closely-conforming opposingshell part 487 of the door 453. A ridge 464 is received into an opening469 of identical shape ensuring that any fluid that strike the interiorof the door 453 are conducted to an interior cavity 464 where theoptical sensor 468 faces inwardly.

In any of the foregoing embodiments, a leak sensor may employ anysuitable technology for detecting leaks, including optical detection,capacitance, conductance, or any other property may be detected.

Referring to FIG. 9, a blood treatment system 508 has a blood treatmentcomponent 510, a blood flow reversal component 512, an air infiltrationdetection component 514, and a leak detection component 516 connected toa patient 518 by arterial and venous blood lines 518 and 520,respectively. In operation, the blood treatment component 510 treatsblood and pumps blood in a normal direction which delivers treated bloodto the patient and withdraws untreated blood through venous and arteriallines 520 and 518, respectively. If a disconnection of the venous lineoccurs, air is drawn in due to the negative pumping pressure, and theinfiltrated air detected by the leak detection component 516. Thedetection of air may cause a controller 506 to generate a signalindicating the event, sound an alarm, and/or enable a safety mode of thetreatment component 510.

In a prior art system conforming to the description of FIG. 9 except forthe additional leak detection component 516, the blood flow reversalcomponent 512 regularly reverses the flow of blood so that anydisconnections or leaks arising in the venous blood line 520 will causeair to be drawn into the venous blood line 520 and conveyed to the airdetection component 514. A problem with the prior art leak detectionscheme is that the patient is subjected repeatedly to blood flowreversal which may be undesirable, for example because it createspatient discomfort or it may add time to the treatment due to theinefficiency of reversing the blood flow repeatedly.

A problem with prior art leak detection mechanisms that rely on pressuremeasurement of the venous blood line is that in order for them to besensitive enough to detect nearly all possible leaks, such systemsproduce too many false alarms. This can lead to so-called operatoralarm-fatigue. Alarm-fatigue can result in the reflexive cancellation ofalarms to the point that the operator may miss a real leak causing harmto the patient.

In the present embodiment, the blood flow reversal component 512 insteadoperates in a forward direction unless a leak is indicated by the leakdetection component 516. When a leak is indicated by the leak detectioncomponent 516, the blood flow reversal component reverses the flow ofblood for an interval to determine if a leak is confirmed by thepresence of air. In embodiments, the leak detection component 516includes a pressure sensor that indicates the pressure in the venousline. The controller receives a signal from the pressure sensorindicating pressure of the blood in the venous line 520 and when thepressure signal corresponds to a characteristic signature of a leak, forexample, the drop in pressure of a certain magnitude over a predefinedinterval of time. If the signature is detected by the controller 506, aleak indication is generated by the controller 506 causing it to triggerthe blood flow reversal component to reverse the flow of blood. Thecontroller may further be configured such that a leak is indicated onlyupon the subsequent detection of air infiltration by the airinfiltration detection component. That is, the controller will onlygenerate a signal indicating the leak and thereby causing a responsesuch as the sounding of an alarm, and/or enablement of a safety mode ofthe treatment component 510, if the initial detection by the blood leakdetection component 516 is confirmed by the detection of air. Otherwise,the normal flow of blood is resumed.

In general, the present system may defined as one in which:

-   -   1. A first indicator of a leak is coupled with a confirmatory        leak detection device. In a narrower embodiment, the        confirmatory leak detection device is triggered by the sensitive        indicator.    -   2. In a variant, the first indicator is sensitive and tends to        produce false positive leak indications when used for detection        of leaks.    -   3. In another variant, combinable with the first and second, the        first leak detection device triggers the confirmatory leak        detection device a predefined number of times in a predefined        period, a leak is indicated by the controller even if the        confirmatory leak detection device fails to confirm the leak.    -   4. In another variant, the confirmatory leak detection device is        one which requires a change of machine operating state.    -   5. In another variant, the change of operating state includes        the reversal of blood flow.    -   6. In another variant, a strong indication of a leak causes the        controller to indicate an alarm without confirmation by flow        reversal, for example, if the magnitude of a detected change in        venous pressure over the predefined interval is beyond a second        threshold that exceeds the threshold that initiates the        confirmatory leak detection process, the leak is automatically        indicated rather than invoking the confirmation process.    -   7. In variants, the venous pressure is measured directly by        measuring pressure in the venous blood line and in another        variant, the venous pressure is measured indirectly using a        pressure sensor responsive to pressure in the effluent line of a        dialyzer or hemofilter.

The algorithm described for detection of a pressure drop ΔP in apredefined interval Δt is illustrated in FIG. 10. Other leak indicatingsignatures of the pressure versus time signal may also be employed. Itmay be noted that the present system allows a very sensitive, andpotentially false-alarm-prone, indicator of leaks to be employed withoutthe undesirable consequence of false alarms or the risk of alarmfatigue. In addition, the present system allows the robust method ofleak detection by flow reversal to be employed in a minimal fashion thatmitigates its undesirable consequences.

The controller 506 may have a user interface 507 that may include, forexample, a display. The user interface 57 and controller may beconfigured to store a log of instances of the sensitive indicator'sindications of a leak along with a record of instances of the invocationof the verification operation. These logs may be displayed on the userinterface 507 and used for monitoring the treatment operation.

Referring now to FIG. 11, a blood treatment machine has a bloodtreatment device 556 such as a dialyzer or blood oxygenator. Medicamentor gas 550, as applicable, may be pumped through the treatment device556 by a pump 558 (or flow regulator as applicable). An air detector 568detects the presence of air in a venous blood line 562. An arterialblood line 564 draw blood from a patient 566 by means of a pump 560. Acontroller 570 receives a signal indicating pressure indicated by avenous pressure sensor 554. In an embodiment, the venous pressure sensor554 includes multiple sensors located at various positions with respectto a venous flow path. In another embodiment, the venous pressure sensoris located near the patient access, for example, a pressure pod formingpart of a disposable access blood set. When the controller identifies apredefined leak signature, such as may be caused by the accidentalwithdrawal of a venous access cannula, it controls the blood pump 560 toreverse direction for a period of time. If the controller detects air bythe air detector 568, an indication of a leak is generated by thecontroller 570 which may be applied to an output device 555 and/orinitiate a safe mode response by the treatment machine 552.

FIG. 12 shows a method for detecting a leak according to embodiments ofthe disclosed subject matter. At S10, a pressure signal is continuouslysampled. At S12, the pressure signal samples are stored to generate apressure versus time signal. The samples may be stored in a buffer tocover a predefined interval of time and a delay may be chosen to providea desired temporal spacing of the samples. Criteria may be applied forrejecting samples or for filtering the buffered samples to removeergodic or random noise, for example, pulsations of a pump, patientmovement, etc. If a signature is detected in the time series of pressuredata generated at step S14, at S16, it is determined if the presentindication is an instance of more than a predefined number of instancesof signature recognition and if so, at step S24 a leak detection signalis output. If at S16, the number of instance of the signature beingrecognized in the predefine interval is not exceeded, then at S18 it isdetermined if the signature exceeds are predefined magnitude or othercharacteristic indicating a strong probability of a leak, for example, apressure change of a predefined high magnitude threshold. If thesignature exceeds this higher probability threshold then control movesto S24, otherwise, at S20, blood flow is reversed for a predefinedperiod. If air is detected during the predefined period, at S24 a leakis indicated otherwise control reverts to S12.

A signature has been identified from logs of actual patient data whichis reasonably predictive of a leak or disconnection. This signature is apressure loss of 17 mm Hg between two pressure plateaus within a narrowinterval of 10 or 15 seconds which may be chosen, for example,responsively to pump speed or nominal flow rate.

In any of the disclosed embodiments, a safe mode may be invoked by thedetection and confirmation of a leak, where the safe mode may includeoutputting an alarm, halting the pumping of blood, generating anautomated phone call to a supervising center, reducing a rate of bloodflow, clamping fluid lines, taking further corrective action to restorepatency to a blood line, and generating a responsive display, forexample, one including instructions for correcting a leak.

FIGS. 13 through 18 show fluid circuit support embodiments and featuresthereof to illustrate subject matter that, among other things, protectstubing against kinking and injury to the tubing and facilitatespackaging.

Referring to FIG. 13, a fluid circuit support 602 is of a generallyplanar form that encloses fluid circuit components of any description,but at least including a tubular portion 604 that extends outside thesupport 602. For example, the enclosed fluid circuit components mayinclude tubular portions such as indicated at 607 and 612 or othercomponents such as connectors or other devices indicated figuratively at617. Components may be exposed for engagement with sensors or actuatorsby openings such as indicated at 611. The support may be formed ofmolded panels that are affixed to each other by standoff dimples asindicated at 615 or otherwise interconnected to create an internal spacein which the internal fluid circuit components may be held. Thestandoffs may be elongate ridges with continuous attachments (e.g.,adhesively bonded, welded, or attached by fasteners) to form a fluidseal as described with reference to the FIGS. 2 and 3A embodiments.

The features shown in FIG. 13 may be employed with any of the disclosedembodiments. For example, a support structure has fence 618 that has ashape whose radius (which may not be constant in embodiments) isselected to prevent a tube 604 from kinking when drawn tightlytherearound as depicted. Another fence is shown at 606 which supportsthe tube 604 both inside and outside. FIG. 16 shows a structure by whichthe fence 604 or 606 may be created, for example, by vacuum forming. Apanel 666A is formed with a ridge 664A to form the fence. A panelportion is shown in section view in FIG. 16. Only one tube 662A is shownadjacent to an outside of the fence 664A. Although the fence is shownwith a rectilinear shape, it may be more tapered to facilitate releasefrom the mold. 667A shows a tube portion internal to the supportstructure similar to 200 discussed above. Reference numeral 660B shows astructure essentially identical structure 660A with similarly referencedelements (except that the letter A is replaced with letter B in thereference numerals). The fence 664B may serve as a support for stackingmultiple support structures as shown in the stack portion 660B and 660A.This may allow the support structures to be stacked without applyingpressure to the tube 662A outside the enclosed part of the supportstructure. It may also aid in the prevention of other outside materials,such as packaging or other objects from deforming the tube 662A (662B).Tubes 662A and 662B represent tubes that extend beyond the supportstructure and which are coiled, for example as discussed above andindicated in FIG. 3A at 270.

Tube 604 is an extension from an internal portion 607 that extendsthrough an opening 604. Although a single tube is shown, multiple tubesmay extend from a single, or from respective openings. A slot 609defines flexible tab portions that overlie the tube 607 partly as itemerges progressively from the interior of the support 602 toward theoutside. A support ramp (not shown in FIG. 13 but see discussion of FIG.17, in particular feature 679) may be provided inside the support 602 toguide the tube upwardly toward, and through, the opening 604. Theextended portion of the tube 609 may be routed around fences 606 and 618as shown. Alternatively, the extended portion of the tube 609 may belooped and tied as illustrated in FIG. 3A. Another form of tube guidehas a slot 608 with openings 610 at either end. A tube on the outside ofthe support 602 can be held in place to help prevent kinking and to helpconfine the external portion of the tube 604 within the perimeter of thesupport 602. The feature may be used with or without the fence features.

In FIG. 14, an internal tube is routed around a fence of dimples 624from which the tube 629 can be pulled in a support device 622. FIG. 15shows a section view of the principle where a tube 653 is held in recess646 formed by opposing standoffs 655 in respective panels 642 and 643 ofa support device. The section view shows internal tube 651 and othercircuit element 654 of arbitrary description enclosed between the panels642 and 643. Tubes 641 and 644 are doubled up in a wider area 648captured similarly to tube 653. The dimples or standoffs may take theform of elongate features rather than low aspect ratio features shown.Standoffs may be bonded, fastened by fasteners, welded or interconnectedby any suitable means. Preferably they are arranged and numbered toprovide rigidity to the support structure 622, 602 (also 200 andsimilar).

The tube 653 (627) end may be pulled out between the dimples 655 (624)that capture it until the drawing may be halted by guides 621, which maybe shaped to relieve strain (thereby prevent kinking) if the tube ispulled to the side. Internal guides 626, 632 may be provided alongstraight and curved sections as required to permit the tube to bewrapped. These guides 626 may be replaced by a continuous fence thatruns along major sides of the support device 622 in embodiments. It canbe visually confirmed that the tube 629 is held safely within theperimeter of the support 622 so that it can be shipped in tight fittingcontainer without risk of kinking or denting the tubes and also so thatthe extended portion of the tube is not injured or strained during otherkinds of storage or handling.

Referring to FIG. 17, a support structure 677 with attached panelportions 672 and 681 that enclose a tube 683 (and optionally, otherelements of a fluid circuit) that extends outside the support structure677 through an opening 675. The opening may include a curved surface 685that supports the tube 683. The panel 672 may have a curved supportfeature 679 as well. A fence 678 is formed around the external face ofthe upper panel 681 which functions to help retain and protect theexternal portion of the tube 683 (the external portion being indicatedat 674). The lower panel 672 may be attached to an underside of theupper panel 681 by suitable standoff features such as indicated at 676to create an enclosed space 671 for fluid circuit components.

Referring to FIG. 18, although in the embodiments described above, fluidcircuit supports were described in terms of examples that employedinterconnected panels. However a variety of different configurations arepossible which may offer the benefit of various features of thedisclosed embodiments. For example, a framed structure such as indicatedat 682 can enclose parts of a fluid circuit and provide an openingthrough which an external tube portion 684 may emerge. Other featuressuch as guides, strain relieving features, releasable connections etc.may also be provided. The frame (or a panel) may also be provided in afully open structure, for example, a single panel or a frame with onlyone side supporting the fluid circuit elements. In the latter case, thefluid circuit elements that do not extend for connection to an outsidefluid source and/or sink may be mounted to the support and the extendedtube or tubes can be releasably attached to the same side or theopposite side of the support.

Referring to FIGS. 19-20, detection and control system features forimplementing embodiments of a system and method according to alternativeembodiments of leak detection in a fluid management system are nowdescribed. A controller 702 is connected to a user interface 718configured to receive commands and output data such as errorindications, alarms, treatment logs, performance logs, treatment status,etc. A fluid management device 720 has sensors and actuators configuredfor performing a process such as an extracorporeal blood treatment orother type of operation, such as infusion, plasmapheresis, or peritonealdialysis. The device 720 may receive disposable components for managingthe flow of fluid while ensuring sterility. The controller 702, userinterface 718, and further components now described may be integrated inthe fluid management device 720 or may be separate components, eitherconnected to it or separate from it. The controller 702 may be one ormore controllers that operate independently or are in communication witheach other or to a common element.

A pressure sensor 704 receives pressure signals indicating fluidpressure at one or more locations of a fluid circuit engaged by device720. The pressure signal may represent pressure in a venous line ofblood treatment circuit, for example, according to a principal one ofthe disclosed embodiments. Alternatively it may be a normally-positivepressure line of a fluid circuit such as the return flow line of aperitoneal dialysis circuit. Alternatively, it may be any fluidconveyance channel of a fluid management circuit.

One or more accelerometers 706 may be connected to a fluid circuit(including the peripheral lines), a patient, patient access, and/or apatient's bed or chair. Alternatively, one or more accelerometers may beconnected to components of a non-treatment circuit to detect vibrations.Such accelerations may be used to detect configuration changes thatmight affect pressure signals and lead to misclassification. Forexample, a patient rolling over in bed may cause a sudden drop inpressure. By applying the accelerometer signal to the controllercontemporaneously with the pressure signal from a positive pressureline, the controller may use both signals to classify a leak. In such acase, the accelerometer signal may be used to inhibit the classificationof the pressure signal as indicating a leak if the acceleration isexperienced contemporaneously with the pressure drop. An accelerometersignal may be classified independently as showing the signature of anevent such as striking on object (e.g., an accelerometer attached to apatient access falling out and hitting the floor).

An imaging device 712 generates an image of a scene, for still imagecapture or video capture, for example. The imaging device may usethermal imaging, optical, ultraviolet, or a combination of the above.The controller may be configured for machine classification of events orconfigurations of the captured scene. For example, a video sequenceindicating a restless patient may be classified as such and a signaloutput indicating the event class and the timing thereof may be appliedto the controller 702. The classifier may recognize a warm or coloredblob as a leak of warm and/or colored fluid such as blood and similarlyoutput an indication of an external flow or leak thereof. The image mayclassify a change in the configuration of a fluid line that indicates akinked line or a change in the position of a line that may correspond toa pressure fluctuation that is detected concurrently. The indication ofthe change in the shape of the fluid line (for example, kinked or simplymoved) may be used by the controller to aid in the machineclassification of fluid line pressure data received by it from pressuresensor 704.

Note as used throughout the specification herein, classifier,classification, and classify may be used to denote machine algorithmsfor converting one or more inputs to an indicator of a class. The termsmay correspond to the simplest classification process which is comparinga raw signal to a predefined range and outputting the result of thecomparison. For example, an analog comparator circuit may be aclassifier as the term is used herein.

A gas detector 714 may be connected to the controller to detect thepresence of gas or air into a fluid line. If a line is under negativepressure, a leak (a type of leak being a disconnection of a patientaccess) may cause the infiltration of air which may be detected whenpumped to an air detector 714. A pump 710 or flow reversing valve 711may be connected to the controller to implement the flow reversalfunction discussed above. A wetness detector 722 may also apply a signalto the controller 702 indicating the presence of fluid outside the fluidcircuit. For example, electrodes of a galvanometer may indicate thepresence of external fluid thereby indicating a leak. The electrodes maybe held in an absorbent material such as an absorbent pad under apatient's access so that leaking fluid can form a conductive path in thewetted pad. A microphone 716 may be used to detect ambient sounds thatmay indicate a leak and/or may disambiguate another signal (e.g.pressure, video, etc.) used by a classification algorithm.

Any and all of the sensor signals described above with reference to FIG.19 (or elsewhere herein) may be combined by the controller 702 in anevent or state classifier to identify an event or state of the systemincluding the classification of a leak. The classification may be doneby any of a variety of classifiers such as explicit rule based networks,supervised learning algorithms, unsupervised learning algorithms, neuralnetwork, etc. Back propagation classifiers may be trained usingtreatment log data. In any of the foregoing, the input vector thatresults in a particular class recognition of a classifier may beidentified as a “signature,” for example an audio signature might thesound of a needle dropping or a patient rolling over in bed. A videosignature might be a growing red blob (spilled blood). A combined inputvector of a video sequence and contemporaneous audio sequence mayprovide a signature of a patient rolling over in bed. A voltage orsignal source and signal receiver or galvanometer 722 may be used todetect continuity in a fluid circuit by applying a voltage and measuringa current or by applying a modulated electrical voltage and measuring acurrent signal across the fluid circuit. This may be used to detect aconductive (e.g., blood or electrolyte) fluid path's continuity. Adetection or failure signal may be applied to the controller 702 aswell.

Referring to FIG. 20, a general method for detecting leaks includes afirst step S102 in which a first one or more signals is analyzed todetermine if there is a leak. The first one or more signals may be,alone or in combination, a weak discriminator and thus, to reduce falsepositives, it may be used to invoke a confirmation process. If a leak isindicated (again, either by a signal or a classifier output responsiveto one or more signals), a confirmation process is invoked at S104. Anexamples is the flow reversal process described above with reference toFIG. 12. Responsively to the confirmation process a refined signal of aleak (or no leak) is generated and used in S108 to invoke a warningsignal output from the UI 718 or a recovery or safe mode process offluid handling device 720. Examples of safe mode include halting pumpsand closing valves to prevent continuation of a leak, output ofinstructions for recovery on the UI 718, and/or an alarm to alert atechnician or operator. S108 may be terminal or, with recovery mayrevert to S102.

As indicated at 750, the initial one or more signals used for step S102may be, or include, as described with reference to FIG. 19, an audiosignature, a pressure signal edge as described with reference to S14 inFIG. 12, a video event signature, wetness indication, or andaccelerometer signature. Any and all of these examples may be combined.As indicated at 752, the confirmation process may be, or include, a flowreversal to generate an air detection (for example, as described withreference to FIG. 12).

As also indicated at 752, the confirmation process S104 may also includean operation in which a pressure signal is monitored during operation ofthe fluid circuit or only at times for the present operation. Theconfiguration or status of the fluid management system is changed topermit the pressure signal to detect a signal that is clearer ordetectable only when the fluid management system acquires that status.An example, is cessation of pumping of fluid and monitoring of thepressure in the line connected to a patient for subtle pressurefluctuations indicating vital signs such as breathing and heart beats.The pressure signal may be filtered digitally to remove noise and otherexternal influences and the result applied to a classifier.

As also indicated at 752, another confirmation process includes theapplication of a voltage to the fluid lines and subsequent detection ofcontinuity with a galvanometer. The technique of using continuity orpassage of a modulated signal (the modulation producing a recognizablesignature that can be filtered out of background noise) confirms theconnection of blood or peritoneal (or other) lines to a patient, whichforms a part of the electrical path of the circuit only when the patientaccess is properly connected. A pressure fluctuation signal, such as apressure fluctuation in the acoustic range, may also be applied to afluid circuit to establish continuity. The received pressure fluctuationsignal may contain transmitted and/or reflected components which may beused to establish, or suggest, the status of a fluid circuit or aconnection thereof.

FIG. 21 is a flow chart showing a procedure that may be used for a firstof the two-stage leak detection system and method described with regardto other embodiments, for example, in place of S14 in FIG. 12. Theprocedure may also be used as a stand-alone method for detecting avenous line disconnect of a blood treatment system or paroxysmal leak inthe venous line. At S202, a buffer is reset by clearing all values ofvenous pressure and arterial pressure edges stored therein if the bloodtreatment system is in an unsteady operating mode. The control flowresets if the machine is in unsteady operating mode as indicated by thearrow 780, clearing the buffer at the same time.

At S204, a new venous pressure and arterial pressure sample are loadedinto the buffer. At S206 the pump speed (blood pump speed=nominal volumerate of blood flow based on pump speed) determines the type of filter tobe applied to the stored stream of arterial pressure samples. At S208,the high and low samples over the previous (in time) 6 arterial samplesand averaging the rest so the filter takes a four-sample average of thesamples remaining after high and low samples are discarded to form asliding window function that is applied retrospectively to generate theslow pump filter. At S210, a notch filter is applied to the samples toremove pump noise from the arterial pressure samples. Alternatively, alow pass filter may be applied with a cutoff at about, or below, thepump pulsation frequency. In embodiments, the pump is a peristaltic orreciprocating pump. The venous pressure signal is searched for a currentvenous pressure plateau and a prior plateau within a prior 60 samples(i.e., 60 seconds). A venous pressure plateau may be defined as one inwhich the pressure values lie within a predefined range for a predefinedinterval. At S216 if a pressure change of some predefined amount, forexample in the range of 12 to 25%, is identified between detectedplateaus, then it is determined if the arterial pressure was stable(within a predefined range of values) during the inter-plateau intervalat S218. A pressure change of 17% was found through experiment toprovide an optimal discriminator for a known hemodialysis systemconfiguration.

The inter-plateau interval (i.e. window) may be defined responsively topump speed, with a longer interval for slower pump speeds. If thefiltered arterial pressure signal was stable, the controller generates asignal indicating a leak, or possible leak, at S220. A stable filteredarterial pressure is defined as a change of less than 10 mmHg betweensamples during the inter-plateau interval. At all decision points S212,S214, S216, and S218, control returns to S202 if the determination isnegative.

FIG. 22 illustrates the pressure fall detection based on plateaudetection and the fall in the filtered venous pressure signal. Theplateau criteria are represented as a box whose height is the predefinedplateau pressure range ΔP and whose width is the predefined plateauinterval Δt. The window (e.g., 10 or 15 samples) over which the pressurefall is required to be found is indicated by “w” and the magnitude by“s.” The plateau value averages are indicated at 788 and the differencebetween them indicated by “s.”

In any of the foregoing embodiments, the pressure used to trigger thesecond stage of the two stage leak detection system may be venous linepressure of a blood treatment system. This pressure may be measuredwithin the blood line of the fluid circuit using a drip chamber,pressure pod, or any other suitable blood line pressure measurementtechnique. It may be also be measured indirectly by measuring thepressure of effluent that is in contact with the venous line through afilter membrane, such as a dialyzer.

In any of the foregoing embodiments, tubular elements may be replacedwith other types of flow channels suitable for conveying fluids.Examples include seam-welded panels forming fluid channels, one or morerigid vessels defining channels therein, rigid or flexible pipenetworks, etc.

In any of the embodiments for a fluid circuit and/or support for thesame, the portion of the tubing that extends beyond the support device(e.g., 200 or 602 or similar) may be for an infusion line to be extendedtoward a patient. Also it (or they, in the case of multiple tubes) maybe for one or two patient access lines of a blood treatment system. Inany of the above embodiments, the fluid circuit may be a disposable unitfor use with an infusion apparatus, an extracorporeal blood treatmentsystem, transfusion or plasmapheresis system, blood oxygenator, or anytype of medical device requiring connection to a patient, a source ordrain, or other connection that must be extended or may be facilitatedby having an elongate attachment or more than one.

It will be appreciated that the modules, processes, systems, andsections described above can be implemented in hardware, hardwareprogrammed by software, software instruction stored on a non-transitorycomputer readable medium or a combination of the above. For example, amethod for detecting leaks using a processor configured to execute asequence of programmed instructions stored on a non-transitory computerreadable medium. For example, the processor can include, but not belimited to, a personal computer or workstation or other such computingsystem that includes a processor, microprocessor, microcontrollerdevice, or is comprised of control logic including integrated circuitssuch as, for example, an Application Specific Integrated Circuit (ASIC).The instructions can be compiled from source code instructions providedin accordance with a programming language such as Java, C++, C#.net orthe like. The instructions can also comprise code and data objectsprovided in accordance with, for example, the Visual Basic™ language,LabVIEW, or another structured or object-oriented programming language.The sequence of programmed instructions and data associated therewithcan be stored in a non-transitory computer-readable medium such as acomputer memory or storage device which may be any suitable memoryapparatus, such as, but not limited to read-only memory (ROM),programmable read-only memory (PROM), electrically erasable programmableread-only memory (EEPROM), random-access memory (RAM), flash memory,disk drive and the like.

Furthermore, the modules, processes, systems, and sections can beimplemented as a single processor or as a distributed processor.Further, it should be appreciated that the steps mentioned above may beperformed on a single or distributed processor (single and/ormulti-core). Also, the processes, modules, and sub-modules described inthe various figures of and for embodiments above may be distributedacross multiple computers or systems or may be co-located in a singleprocessor or system. Exemplary structural embodiment alternativessuitable for implementing the modules, sections, systems, means, orprocesses described herein are provided below.

The modules, processors or systems described above can be implemented asa programmed general purpose computer, an electronic device programmedwith microcode, a hard-wired analog logic circuit, software stored on acomputer-readable medium or signal, an optical computing device, anetworked system of electronic and/or optical devices, a special purposecomputing device, an integrated circuit device, a semiconductor chip,and a software module or object stored on a computer-readable medium orsignal, for example.

Embodiments of the method and system (or their sub-components ormodules), may be implemented on a general-purpose computer, aspecial-purpose computer, a programmed microprocessor or microcontrollerand peripheral integrated circuit element, an ASIC or other integratedcircuit, a digital signal processor, a hardwired electronic or logiccircuit such as a discrete element circuit, a programmed logic circuitsuch as a programmable logic device (PLD), programmable logic array(PLA), field-programmable gate array (FPGA), programmable array logic(PAL) device, or the like. In general, any process capable ofimplementing the functions or steps described herein can be used toimplement embodiments of the method, system, or a computer programproduct (software program stored on a non-transitory computer readablemedium).

Furthermore, embodiments of the disclosed method, system, and computerprogram product may be readily implemented, fully or partially, insoftware using, for example, object or object-oriented softwaredevelopment environments that provide portable source code that can beused on a variety of computer platforms. Alternatively, embodiments ofthe disclosed method, system, and computer program product can beimplemented partially or fully in hardware using, for example, standardlogic circuits or a very-large-scale integration (VLSI) design. Otherhardware or software can be used to implement embodiments depending onthe speed and/or efficiency requirements of the systems, the particularfunction, and/or particular software or hardware system, microprocessor,or microcomputer being utilized. Embodiments of the method, system, andcomputer program product can be implemented in hardware and/or softwareusing any known or later developed systems or structures, devices and/orsoftware by those of ordinary skill in the applicable art from thefunction description provided herein and with a general basic knowledgeof medical device software and/or computer programming arts.

Moreover, embodiments of the disclosed method, system, and computerprogram product can be implemented in software executed on a programmedgeneral purpose computer, a special purpose computer, a microprocessor,or the like.

It is, thus, apparent that there is provided, in accordance with thepresent disclosure, leak detection methods, devices and systems. Manyalternatives, modifications, and variations are enabled by the presentdisclosure. Features of the disclosed embodiments can be combined,rearranged, omitted, etc., within the scope of the invention to produceadditional embodiments. Furthermore, certain features may sometimes beused to advantage without a corresponding use of other features.Accordingly, Applicants intend to embrace all such alternatives,modifications, equivalents, and variations that are within the spiritand scope of the present invention.

The invention claimed is:
 1. A method for performing a blood treatment,comprising: pumping blood to a patient through a first blood line with ablood treatment machine; receiving at a controller of said bloodtreatment machine a first signal indicating a suspected leak in saidfirst blood line based on a first leak detection operation; at saidcontroller, responsively to said first signal, commanding a leakverification operation that is different from the first leak detectionoperation and verifies whether the suspected leak is an actual leak;receiving a second signal indicating a result of the leak verificationoperation that indicates whether the suspected leak in said first bloodline is verified as the actual leak; and at said controller, generatinga leak indicating signal if said second signal indicates that thesuspected leak is verified as the actual leak.
 2. The method of claim 1,wherein said controller is configured to control a rate and direction ofsaid pumping and said leak verification operation includes reversing aflow of blood in said first blood line and detecting air in said firstblood line.
 3. The method of claim 1, further comprising: generatingsaid first signal, wherein said generating said first signal includesdetecting a change of pressure in said first blood line.
 4. The methodof claim 1, further comprising: generating said first signal, whereinsaid generating said first signal includes detecting a threshold rate ofchange of pressure in said first blood line of a predefined magnitudebetween adjacent intervals where the pressure remains within apredefined stable range.
 5. The method of claim 1, further comprising:generating said first signal, wherein said generating said first signalincludes detecting a characteristic of a pressure versus time signalcharacterizing a flow in said first blood line.
 6. A system forperforming a blood treatment, comprising: a blood treatment componentincluding a fluid pump configured to pump blood to a patient through afirst blood line; and a controller configured to control flow of theblood through the blood treatment component, wherein said controller isfurther configured to receive a first signal indicating a suspected leakin said first blood line based on a first leak detection operation, saidcontroller is further configured to, responsively to said first signal,command a leak verification operation that is different from the firstleak detection operation and verifies whether the suspected leak is anactual leak and receive a second signal indicating whether the suspectedleak in said first blood line is verified as the actual leak, and saidcontroller is further configured to generate a leak-indicating signalresponsively to said second signal.
 7. The system of claim 6, whereinsaid controller is further configured to control a rate and direction ofsaid pumping, and said leak verification operation includes reversing aflow of blood in said first blood line and detecting air in said firstblood line.
 8. The system of claim 6, wherein said controller is furtherconfigured to generate said first signal responsively to a detection ofa change of pressure in said first blood line.
 9. The system of claim 6,wherein said controller is further configured to generate said firstsignal responsively to a detection of a rate of change of pressure insaid first blood line.
 10. The system of claim 6, wherein saidcontroller is configured to generate said first signal responsively to adetection of a characteristic of a pressure versus time signalcharacterizing a flow in said first blood line.
 11. A blood treatmentapparatus, comprising: a blood treatment component configured to pumpblood from an arterial blood line to a venous blood line; a leak sensorconfigured to detect a suspected leak with a probability of less thanunity in the venous blood line and output a first signal indicating thesuspected leak; an air detector configured to detect infiltration of airinto said venous blood line; a blood flow reversing device controlled bya controller; and the controller, wherein the controller is configuredto receive the first signal from said leak sensor, and to reverse flowresponsively to the first signal from said leak sensor such that airinfiltrating said venous blood line is detected by said air detector tothereby verify the suspected leak as an actual leak.
 12. The apparatusof claim 11, wherein the leak sensor includes a pressure sensorconfigured to detect pressure changes in said venous blood line.
 13. Theapparatus of claim 11, wherein the leak sensor includes a data storeconfigured to record a time series of pressure samples representingpressure in said venous blood line and a processor configured todetermine a magnitude of a change in pressure within a predefined timeinterval.
 14. The apparatus of claim 11, wherein the leak sensorincludes a data store configured to record a time series of pressuresamples representing pressure in said venous blood line and a processorconfigured to determine a magnitude of a change in pressure within apredefined time interval and to indicate a leak when a rate of change inpressure exceeds a predefined range.